One of the common problems associated with residential casement windows is sash sag. Sash sag is the expression used to describe the misalignment of the sash to the casement window frame. The casement sash tends to tilt outwardly because of the location of the center of gravity.
Sash sag is usually caused by poor installation of the window unit into the home; i.e., the frame is not properly squared. Poor hinge positioning by the window manufacturer also causes sash sag. Sash sag could be easily corrected in the field during installation if the position of the hinge were adjustable. Unfortunately, in conventional commercial casement sash units, the position of the hinge is no adjustable.